So my 508 hsas been sitting a couple days and when I started it today, i could hardly get it to rev from idle. It seemed to rev ok above idle, if I kept the turbo lit. I have a soundbite but don't see any way to add it here.
Could it be that the start/stop battery, which is as old as the car(2013) is done and me leaving the car for a couple days, then starting it, the battery could not give the power needed by the injection pump to pump diesel in from idle?
problem goes away when car has been driven a while/ warmed up.
No fault codes in torque with bluetooth obd. Couldn't get wifi obd to talk to torque.
only have a very old lexia.

This means there was an internal fault detected in the Engine Management ECU for 500ms.Conditions of Fault: When engine is running.Disappearance of the Fault: Driving for 5 MinutesDowngrade mode: The Start Stop system will not automatically restart the engine - you must restart it with the key.Symptoms: Jerking / Stalling, Starting Problem, Lack of PowerSuspect Areas: Engine Management ECU.

Fault P0685: Power Relay Control - open Circuit.Description: Electrical fault detected for 5s.Condition for Fault:Ignition on or Engine Running.
There are no downgrade moes for this specific fault.Symptoms: Jerking / Stalling, Starting Problem, Lack of PowerSuspect Areas: Power relay, Electrical Harnesses or Connectors.

Fault B1003 (BSI): There is not specific error except to say it means there is a configuration fault in the BSI. Something has been changed in the BSI or one of the other ECUs that also get written to the BSI and the entry or configuration parameter is not correct most likely. See Following:

Fault B1003 (Multi-Function Screen): Configuration fault.Description: Configuration of one or more parameters not correctly or not completely performed.Conditions for Disappearance of the Fault: The configuration has been carried out successfully.Symptoms:No display, or incorrect display of the data, or the screen will not turn on or turn off.Suspect Areas: Multifunction Screen / or incorrect configuration.

So you obviously have PP2000 - have you changed any settings anywhere - specifically those related to the Head Unit o the screen? The last 2 errors will be related as they are written tot he ECU Head unit and also the BSI, hence the 2 faults and the reason why the BSI knows something is wring, but is not related to the BSI itself.

The main fault would certainly seem to be with the Stop Start system and would seem to indicate the starter inhibitor is not working properly. It could also be the result of that mechanical noise in your video.

It's diagbox, not PP2000.
Never did anything other than clear faults, and only cleated the faults to see if they would come back because of the revving from cold issue

The ECU faults cleared ok and never came back.

Start/Stop works ok.

Fault disappears when engine warm.

Old dealer note in along with manual saying hesitation in car, no faults, but reprogrammed injectors and apparently fault went away. previous owner says they never had anything like this.
But, if car was warm when mechanic took it for run after reprogamming injectors, the fault would have disappeared anyway.
Previous owner would have been hyper gentle with the car, and hardly used it cos it has less than 17000 miles on it.
When I got the car, i gave it a good run and also did the reset of the gearbox thing - start from standing start, and take off quick, making car rev all the way up till it auto changed, right up till 4th gear.

So what could cause this kind of fault that doesn't show up in diags AND goes away when warmed up?

Anyway - to answer your question, something that does not result in a fault code being triggered - or that may not in itself have an ECU or sensor attached to an ECU. It does sound a bit rough... Maybe you need someone to revi it whilst you are recoding a video in the engine bay to try and hone in on the area...

Ok, so from your video - although you were whizzing about a bit quick, it certainly looked like the Dynamic tensioner roller - I may be mistaken, but it did seem to rattle in unison - I've marked it in yellow:

and below is the part - item (4). You have a reversible alternator on the vehicle. I know there was another member who had an issue with his - let me try and find it....

I would suspect this is one of the injectors beginning to give out, not uncommon on DV6C engines.... Try checking the live data on injector corrections in Diagbox as you rev the engine and see what it shows.

Go into the Engine ECU, and then 'Standard Parameter' measurements, then injection of similar, and you should then be able to see what corrections it is applying to the injectors. Is one (or more) different from the others? Does one of them significantly change as you rev the engine when it coughs? You might also be able go into custom (I can't remember the exact words) parameters and this might allow you to graph the corrections. I would also look at the live data for the EGR valve - does it respond quickly to requests, and is the output position stably tracking the requested position?